Method and apparatus for introducing lines through conduits



Oct. 31, 1961 J HAMRlcK 3,006,607

METHOD AND APPARATUS FOR INTRODUCING LINES THROUGH CONDUITS Filed Oct.22, 1959 C Q H \O INVENTOR JAMEs C. HAMEJCK ATTORNEYS United StatesPatent 3,006,607 METHOD AND APPARATUS FOR INTRODUCING LKNES THROUGHCONDUITS James C. Hamrick, Charlotte, N.C., assignor to Jet LineProducts, Inc, Charlotte, N.C., a corporation of North Carolina FiledOct. 22, 1959, Ser. No. 848,119 7 Claims. (Cl. 254-1344) This inventionrelates to a method and apparatus for introducing a guide line through aconduit, the guide line thereafter being connected to a relatively rigidline or similar elongated article-such as an electrical cable orconductor, a lengthy thermosensitive element, etc.- for drawing therelatively rigid line or similar elongated article within the conduit bypulling on the guide line.

Previous attempts to pass a guide line through a conduit have includedthe use of fluid pressure to force a projectile through the conduit, theprojectile having one end of the guide line attached to its trailing endand the fluid pressure being continuously applied against the rear endof the projectile to thrust it forwardly. The frictional resistanceencountered between the projectile, its attached line and the conduitincreases markedly as the projectile is thrust through the conduitbecause of the increasing frictional drag of the line as more of it ispulled into the conduit. The projectile itself is relatively heavy,thereby presenting considerable weight which must be overcome by thefluid pressure before forward movement of the projectile is effected.

It has also been proposed to introduce a guide line through a conduit byproviding a projectile which is adapted to form a seal with the internalwall surface of the conduit, wherein a reel of line is housed within theprojectile with its longitudinal axis transversely disposed to thelongitudinal extent of the projectile and the conduit. Fluid pressure isthen continuously applied against the rear end of the projectile to pushit forwardly. As the projectile moves forwardly, the line from the reelis payed out in the conduit. This practice is relatively slow andineficient because the conduit rnust be leak-proof and of substantiallyuniform diameter throughout its length. The projectile must be of aparticular size \m'th respect to the conduit through which it is to bepassed to insure a good seal therebetween. Moreover, the frictionalresistance created by such a device requires a substantially unlimitedsource of fluid pressure to enable the projectile to pass completelythrough the conduit.

in co-pending United States patent application Serial Number 674,930filed July 29, 1957, now US. Patent 2,930,584 issued March 29, 1960,there is disclosed a self-propelled cartridge projectile which isutilized in introducing an attached guide line through a conduit. Whilethe method and apparatus disclosed in the aforesaid application areeminently satisfactory for introducing a guide line through a conduit,diificulties are encountered Where the conduit possesses a relativelysmall internal diameter of the order of /2 or Under such conditions, thecompulsory size limitations placed on the cartridge projectile to enableit to pass freely within the conduit unduly restrict the quantity ofgaseous pressure it may hold and which serves as its propellant.Accordingly, all of the gaseous pressure may be dissipated from thecartridge projectile before it has completed its journey through theconduit.

In all of the above-noted approaches, some form of rigid, relativelyheavy projectile is employed as a carrier to introduce the guide linethrough a conduit. A conduit having one or more angular bends thereincreates special problems which, although overcome to some extent,restrict the instances where such approaches may be successfullyemployed. In many cases, a sharp angular bend in a conduit will preventconventional procedures for introducing a guide line through the conduitfrom accomplishing the desired results. The sharp angular bend may causethe line-carrying projectile to become wedged in the conduit whereuponmeasures must be taken to extricate the projectile from the conduitresulting in prolonged delays before the introduction of the guide linethrough the conduit may be accomplished.

It is an object of the present invention to provide an improved methodof introducing a guide line through a conduit by utilizing a packagecontaining a supply of line which has an outer diameter smaller than theinternal diameter of the conduit and which may be blown through theconduit by fluid pressure, to cause the line to be payed off from thepackage and laid in the conduit as the package moves therethrough. Theimproved method contemplates the application of a jet of fluid pressureof a relatively high magnitude against the package to thrust the packagerapidly forward, the package thereafter passing through the conduit onits forward momentum built up by the jet of fluid pressure. In addition,a continuous application of fluid pressure at a lower magnitude againstthe package could be employed to blow the package through the conduit.

It is another object of this invention to provide a method ofintroducing a guide line through a conduit having one or more angularbends therein by utilizing a flexible package containing a supply ofline which has an outer diameter smaller than the internal diameter ofthe conduit, directing fluid pressure against the package to propel itthrough the conduit, and flexing the package to substantially conform toeach angular bend in the conduit as it passes therethrough, while payingout line from the package as it moves through the conduit.

It is another object of this invention to provide apparatus forintroducing a guide line through a conduit wherein the apparatuscomprises a lightweight line package having a smaller outer diameterthan the internal diameter of the conduit, a source of fluid pressure,and means for directing the fluid pressure against the rear end of theline package for freely thrusting it through the conduit, the line beingpayed out from the package as it moves through the conduit.

Another object of the present invention is to provide a method andapparatus for introducing a guide line through a conduit whichcompletely eliminates the possibility that the conduit may becomepermanently blocked by the instrumentality employed as the line carrier.One impressive advantage of the flexible lightweight line package asemployed in the present instance over conventional procedures resides inthe fact that permanent blockage of the conduit, where a line carrierhas become wedged in a constricted portion of the conduit and alletforts to dislodge it have failed, cannot occur. Should the linepackage become temporarily wedged in the conduit, more line may beremoved from the package by pulling on the end extending from theconduit until the wedged condition is relieved.

Some of the objects of the invention having been stated, other objectswill appear as the description proceeds, when taken in connection withthe accompanying drawings, in which FIGURE 1 is a schematic view showinga conduit extending through a building, wherein a line package is beingpassed through the conduit in accordance with the present invention;

FIGURE 2 is a greatly enlarged fragmentary longitudinal sectional viewof the line package traveling through the conduit, taken along line 22in FIGURE 1; and

FIGURE 3 is a greatly enlarged sectional view of a conduit having anangular bend therein, the line package being shown in elevation as itpasses through the bend.

Referring more specifically to the drawings, FIGURE 1 schematicallyillustrates the present method and apparatus for introducing a guideline through a conduit. Thus, in FIGURE 1 a conduit C extends throughouta building, the conduit C having angular bends therein at variouslocations along its extent and being interrupted at one or more placesfor receiving junction boxes I.

In practicing the improved method, a line package is employed as themedium for introducinga guide line through the conduit. The line packagecomprises a casing or wrapping 11 of suitable material, such as paper orplastic, the casing 11 having an elongated substantially cylindricalshape. A supply of pliable line L is wound in an elongated cylindricalroll 12 which fits snugly within the casing 11. The cylindrical roll 12of line L is preferably wound so that the line L may be unwound from itscenter outwardly. In this manner, the outer diameter of the line package10 and substantial frictional engagement between the cylindrical roll 12and the casing 11 are maintained as the line L is dispensed from theline package 10 as subsequently described.

The line package 10 is flexible in nature, such flexibility beingenhanced by means in the form of one or more score lines 13 provided inthe casing 11 medially of its ends and eachsuch score line 13 serving asa weakened portion on the casing 11. A suitable source of fluid pressurewhich may be in the form of a portable container 14 of compressed gaspreferably having a magnitude of 300 pounds per square inch (as shown inFIGURE 1) communicates with one end of the conduit C by means offlexible tubing 15. The supply of fluid pressure to one end of theconduit C is controlled by suitable means, such as a manually operablevalve 16.

In practicing the method, one end of the line L is withdrawn from thecylindrical roll 12 and secured to a point located outside of theconduit C. The line package 10 is then inserted in one end of theconduit C and the flexible tubing 15 is positioned with its outlet enddisposed in the .conduit C behind the rear end of the line package 10.

Upon opening the valve 16, the line package 10 is subjected to a jet offluid pressure from the portable container 14. It will be observed thata major portion of the fluid pressure impinges upon the rear end of theline package 10, while a proportionally smaller amount is permitted topass beyond the line package 10 in the space between the conduit C andthe line package 10. The lightweight line package 10 is immediatelythrust forward in the conduit C by the impact of the fluid pressureagainst its rear end. In this connection, it will be noted that the linepackage 10 although having an outer diameter which is smaller than theinternal diameter of the conduit C, possesses a cross-sectional areawhich substantially fills the conduit C. The initial forward thrustimparted to the line package 10 by the fluid pressure builds up forwardmomentum enabling the line package 10 to travel through the conduit Cand out of its opposite end. As the line package 10 moves through theconduit, the line L is unwound from the cylindrical roll 12 and payedout in the conduit C. Since the line L is unwound from the center of thecylindrical roll 12 outwardly, the outer diameter of the cylindricalroll 12 is unchanged, thereby maintaining the same cross-sectionaldimensions for the line package 10 as it travels through the conduit C.

Although the line package 10 possesses considerable flexibility, thisflexibility is enhanced by the one or more score lines 13 located alongits longitudinal extent. Preferably, the outer casing or wrapping 11 ofthe line package 10 is broken along each score line 13 before the linepackage 10 is inserted within the conduit C to increase the flexibilityof the line package 10, thereby enabling it to better negotiate sharpangular bends in the conduit C, as illustrated in FIGURE 3. The linepackage 10, upon encountering an angular bend in the conduit C, flexesto conform with the bend as it passes therethrough.

In the installation of the conduit C during construction work, it islikely that one or more crimped places K (FIGURE 3) will be formedthereon by the striking of a rigid object, such as a tool, against theconduit C. The crimp K creates a reduced internal diameter portion forthe conduit C where it is located and may seriously impede or actuallystop a conventional rigid line-carrying projectile from completing itsjourney through the conduit C. In the present instance, the highlyflexible line package 10 may conform to the crimp .K for passing throughthe reduced internal diameter portion of the conduit C caused thereby.There may be occasions when the crimp K is extremely severe. Under suchconditions, a rigid projectile is apt to become hopelessly wedged in theconduit C. On the other hand, the line package 10 while it may betemporarily lodged in the conduit C because of the impediment created bythe crimp K, can always be dislodged or removed. To dislodge the linepackage 10, an operator may pull on the line L extending from the end ofthe conduit C through which the line package 10 entered to removeadditional line from the cylindrical roll 12. The operator continues toremove line from the cylindrical roll 12 in this manner until the linepackage 19 can be blown past the impediment by a jet of fluid pressurefUnder the Worst possible constricted condition in the conduit C, it maybe necessary to withdraw all of the line L from the line package 10 inthe manner indicated to remove the line package It from the conduit C.Regardless of the nature of angular bends and crimps K in the conduit C,the line package 10 used in the present method cannot became permanentlylodged therein.

It has been determined that a source of fluid pressure having arelatively high magnitude is capable of thrusting the line package 10through a relatively long conduit C by directing a jet of such pressureagainst the rear end of the line package 10, rather than directing acontinuous stream of fluid pressure thereagainst. The momentum initiallybuilt up in the line package 10 by the sudden impact of the jet of fluidpressure is normally suflicient to thrust the line package 1!)completely through the conduit C. Of course, the present invention alsocontemplates the use of a fluid pressure source having a somewhat lessermagnitude in which fluid pressure is continuously applied against therear end of the line package 10 until it has completed its journeythrough the conduit C. The lightweight line package 10 is propelledthrough the conduit C at a high rate of speed, enabling it to jumpacross interruptions in the conduit C created by junction boxes I.

In the drawings and specification there has been set forth a preferredembodiment of the invention, and although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation, the scope of the invention being defined in theclaims.

I claim:

1. The method of introducing a pliable line through a conduit having atleast one angular bend therein comprisrng the steps of directing fluidpressure against a flexible line package having an outer diameter lessthan the internal diameter of the conduit, blowing the line packagefreely through the conduit by the fluid pressure, guiding the linepackage past all angular bends in the conduit by flexing the linepackage to substantially conform to the shape of each such angular bendas it moves therethrough, and paying out line from the line package inresponse to the movement of the line package through the conduit.

2. The method of introducing a pliable line through a conduit having atleast one angular bend therein comprising the steps of directing a jetof fluid pressure against the rear end of a flexible line package havingan outer diameter less than the internal diameter of the conduit toinduce rapid forward movement of therline package, passing the linepackage through the conduit by the forward momentum built up by the jetof fluid pressure, guiding the line package past all angular bends inthe conduit by flexing the line package to substantially conform to theshape of each such angular bend at is moves therethrough, and paying outline from the line package in response to the movement of the linepackage through the conduit.

3. The method of passing a flexible line carrier through a conduithaving at least one angular bend therein, wherein the line carrier hasan outer diameter less than the internal diameter of the conduit,comprising the steps of directing fluid pressure against the linecarrier, blowing the line carrier freely through the conduit by thefluid pressure and guiding the line carrier past all angular bends inthe conduit by flexing the line carrier to substantially conform to theshape of each such angular bend as it moves therethrough.

4. Apparatus for introducing a line through a conduit comprising anelongated line package having a casing with an outer diameter less thanthe internal diameter of the conduit and a supply of line wound in acylindrical roll fitting snugly within said casings, said casing andsaid cylindrical roll of line being flexible throughout theirlongitudinal extents, a source of fluid pressure, means for directingfluid pressure from said source against said package to propel saidpackage through the conduit, and said line being unwound from thecylindrical roll and payed out in the conduit in response to themovement of said package through the conduit.

5. Apparatus for introducing a line through a conduit comprising anelongated cylindrical line package having a cylindrical casing with anouter diameter less than the internal diameter of the conduit and asupply of line wound in a cylindrical roll fitting snugly Within saidcylindrical casing, said cylindrical casing and said cylindrical roll ofline being flexible throughout their longitudinal extents to provideflexibility for said line package along its entire length, a source offluid pressure, means for directing fluid pressure from said sourceagainst said package to propel said package through the conduit, saidline being unwound from the cylindrical roll and payed out in theconduit in response to the movement of said package through the conduit,and said package flexing at any point along its length to conform toirregularities in the conduit for moving therethrough,

6. Apparatus for introducing a line through a conduit comprising anelongated cylindrical line package having an outer diameter less thanthe internal diameter of the conduit and a supply of line wound in acylindrical roll fitting snugly therewithin, means on said packageproviding a weakened portion medially of its ends, a source of fluidpressure, means for directing fluid pressure from said source againstsaid package to propel said package through the conduit, said line beingunwound from the cylindrical roll and payed out in the conduit inresponse to the movement of said package through the conduit and saidpackage bending in the area of said means providing the weakened portionthereon for passing through an angular bend in the conduit.

7. Apparatus for introducing a line through a conduit comprising asupply of line wound in an elongated roll having an outer diameter lessthan the internal diameter of the conduit, said elongated roll beingflexible throughout its longitudinal extent, a source of fluid pressure,means for directing fluid pressure from said source against saidelongated roll to propel said elongated roll through the conduit, andsaid line being unwound from said elongated roll and payed out in theconduit in response to the movement of said elongated roll through theconduit.

References Cited in the tile of this patent UNITED STATES PATENTS252,956 Loane Ian. 31, 1882 395,881 Cunningham Jan. 8, 1889 1,072,969McCreary Sept. 9, 1913 2,470,338 Chilton May 17, 1949 2,822,146 Ridgerset a1. Feb. 4, 1958

